Laserfiche WebLink
IV <br /> 6.0 Backfill Procedures f <br /> The East Excavation (location of the former gasoline UST) was backfilled with both <br /> clean native soil from the excavation and imported fill material. The native soil was <br /> placed in 1' to 2' lifts, and compacted using a sheepsfoot and water. Clean pea gravel <br /> was used to fill the remainder of the excavation to a depth of 6" BSG, and roadbase <br /> completed the backfill to surface. Copies of the load sheets describing the type, <br /> source, and quantity of material used are included as Appendix D. <br /> 7.0 Site Geology <br /> The excavation penetrated sediments consisting of unconsolidated clayey gravel, silty <br /> clay, clayey silt and sandy silt. These lithologies are representative of the Quaternary <br /> fan and basin deposits that underlie the site (Calif. Div. Mines and Geol., 1971). The <br /> depth to groundwater is estimated to range between 50 and 75 feet BSG. This is <br /> based on information from the San .Joaquin County Flood Control and Water <br /> Conservation Department for a well close to the subject site, which recorded a historic <br /> high of 50' BSG in 1986 and a depth to groundwater of 75' in Spring 1992. <br /> Groundwater was not encountered during the excavation operations. <br /> 8.0 Conclusions <br /> The site remediation operations consisted of excavating the two plumes of <br /> hydrocarbon impacted soil which existed at the subject site. The analytical results of <br /> both rounds of confirmation soil samples collected from the base and sidewalls of the <br /> two excavations indicated non-detectable concentrations of all analytes, with the <br /> exception of minimal concentrations of TOG in one (1) of the eleven (11) samples <br /> collected from the West Excavation. Based on analytical laboratory results and field <br /> observations, it is the opinion of AGI that the hydrocarbon impacted soil was <br /> successfully removed during excavation. <br /> 9.0 Recommendations <br /> Based upon the results and conclusions outlined in the previous sections of this <br /> interim site remediation report and conversations with Mr. Michael Infurna of the <br /> County, AGI recommends the following course of action. <br /> A copy of this report should be forwarded to the County requesting that no <br /> further excavation is necessary at the East and West Excavations. <br /> i <br /> 9of10 <br />